* Add HOLD_ON_OTHER_KEY_PRESS option for dual-role keys
Implement an additional option for dual-role keys which converts the
dual-role key press into a hold action immediately when another key is
pressed (this is different from the existing PERMISSIVE_HOLD option,
which selects the hold action when another key is tapped (pressed and
then released) while the dual-role key is pressed). The Mod-Tap keys
already behave in a similar way, unless the IGNORE_MOD_TAP_INTERRUPT
option is enabled (but with some additional delays); the added option
makes this behavior available for all other kinds of dual-role keys.
* [Docs] Update tap-hold docs for HOLD_ON_OTHER_KEY_PRESS
Document the newly added HOLD_ON_OTHER_KEY_PRESS option and update the
documentation for closely related options (PERMISSIVE_HOLD and
IGNORE_MOD_TAP_INTERRUPT).
Use Layer Tap instead of Mod Tap in examples for PERMISSIVE_HOLD and
HOLD_ON_OTHER_KEY_PRESS, because the effect of using these options with
Mod Tap keys is mostly invisible without IGNORE_MOD_TAP_INTERRUPT.
Add comments before return statements in sample implementations of
`get_ignore_mod_tap_interrupt()`, `get_hold_on_other_key_press()` and
`get_permissive_hold()`.
Thanks to @Erovia and @precondition for comments and suggestions to
improve the documentation.